#include<stdio.h>
#include<unistd.h>

int g_val = 100;
int main()
{
    pid_t id = fork();

    if(id == 0)
    {
        int cnt = 0;

        while(1)
        {
            printf("i am child,pid:%d,ppid:%d,g_val:%d,&g_val:%p\n",getpid(),getppid(),
                    g_val,&g_val);
            sleep(1);
            cnt++;
            if(cnt==5)
            {
                g_val = 200;
                printf("child change g_val 100 -> 200\n");
            }
        }
    }
   else 
   {
       
        while(1)
        {
            printf("i am father,pid:%d,ppid:%d,g_val:%d,&g_val:%p\n",getpid(),getppid(),
                    g_val,&g_val);
            sleep(1);

         }
   }

    return 0;
}
